Communication system



2 Sheets--Shefel 1 F. H. HANLEYv COMMUNICATION SYSTEM l Filed May 9,1959 .Emmaus .my 1s, 1941.

July 15, 1941. F. H. ANL-EY' 2,248,923

COMMUNICATION SYSTEM Filed May 9, 19:59 2 sheets-sheet 24 1 21 l 1 1 i2u. I. i@ llllllllllll-lv POLA'LZED IIIIHIl POLAR/250 R12-PEA TER/NvEA/rJoR I FH H/VL Ey ATTORNEY Patented July 15, 1941 UNITED STATESParar ferries v g COMMUNICATION SYSTEM Frank 'Harold Hanley, Butler, N.J., assignor to American Telephone and Telegraph Company, a corporationof New York Application May 9, 1939, Serial No. 272,675

` 7 Claims. (Cl. 17g-3.1)

This invention relates to communication systems and particularly totelegraph systems where intelligence is transmitted from point to pointby permutation code. f

The object of the invention is to provide service for a plurality ofsubscribers at one point to a corresponding plurality of subscribers atanother point over a common channel which appears to each subscriber asa direct individual and Permanently established connection to anotherparticular subscriber.

In accordance with this invention a sequence circuit is provided foralternately giving the various transmitting stations command overvthecommon channel so as to allow the alternate transmission of a charactercode from each station in a condition to transmit. When only a singlestation is in such a condition then that station takes the full time ofthe common channel but when more than one is in a condition to ftransmit then the time is divided share and share alike.

I am aware of an arrangement disclosed in Patent 2,171,542, granted toCunningham et al.

Sept. 5, 1939, wherein the time of a common.

channel linking a pair of synchronouslyoperating distributors is dividedamong connections which appear to the subscribers to be directindividual and permanently established connections between correspondinglocal stations at op- I Vposite ends of such channel. I am aware of thefact that such appearance in this disclosure is maintained by thetransmission between each character code over such common channel ofsignals identifying that apparent connection l' which is next to havethe use of such common channel.

I am further aware of the disclosure in patent granted to Borgeson etal. Ser. No. 174,468, led Nov. 13,1937, which issued on Dec. 10, 1940 asPatent No. 2,224,250 wherein start-stop distribusignals together with acircuit arrangement whereby the time of inactive connections is givenover to and divided equally and automatically among active connections.

VMy contribution to this art is an arrangement employing start-stopdistributing means at the opposite ends of a common channel wherein theidentification of the next in turn active connection to be given commandof the common channel is made invariably at the same point in theoperation of the said start-stop apparatus. In my system, upon theexclusive appropriation/of the common channel to a connection there isfirst transmitted what may be termed an appropriation signal notifyingthe start-,stop apparatus at the distant end that the common channel hasbeen appropriated and that the apparatusrat the near end has started.This acts to start the apparatus at the far end and to immediatelyprepare selecting apparatus thereat for the reception of the identifyingsignal. identification signal then follows. According to my invention,the identication of a connection is, made by different character signalsrather than differently timed signals.` This is of great advantage inthesaving of time since the time for the operation does not haVeto extendover ay number of distributor segments equal to the number ofconnections butis carried out in the space of ay single segment.

In the specific embodiment of`my `invention the identification signaltakes the form of either a Vmark or a space signalbut itrwill beunderstood that I contemplate other forms of signals, all of whicharetransmitted at the same instant and over an equal length period.

A feature of the invention is an arrangement `whereby the time usuallyused in start-stop permutation code sending `for sending the start sig-Y nal is used for sending, instead, an identiiication signal to denotethe particular station lwhich is about to transmit a code and to selectto receive thatcode the particular receiving station which formsaseeminglypermanently established connected pair with the saidparticular station about to transmit. The usual start pulse is thengenerated locally at the receiving end of the com- Amon channel andtransmitted to the receiving station in time to start the receivingapparatus thereat to properly receive the transmitted per- V mutationcode. v

The drawings comprise two sheets of drawings which, when placed asindicated in Fig.A 1, form a circuit diagram illustrating the invention.

Let us rst assume that station A in the upper left-hand corner of Fig. 2is in condition to transmit. This means that sufficient tape I will havebeen perforated by the perforator 2 to cause the closure of tape switch3. Thereupon a circuit is closed from ground through tape switch 3,Winding of relay 4, the back contact and armature of relay 1 to positivebattery. Relay 4 is energized and closes a circuit from ground, theinner lower armature and back contact of relay 8, the inner lowerarmature and front contact of relay 4, the winding of relay 5 and thewinding of relay 6 to positive battery. Relays 5 and 6 become energizedand lock in a circuit including ground, the upper armature and frontcontact of relay 4 and the front contact and upper armature of relay 5.

Relay 4 also closes a circuit from negative battery through its outerlower armature and front contact, winding of latch magnet I2, segmentI3, brush I4 and segment I5 to positive battery, whereupon the latch I6is-withdrawn from engagement with arm I1 and this arm carrying thebrushes I4 and I8 begins to revolve.

Th-e device generally at the right of Fig. 2 is a start-Stop typedistributor. A motor I9 energized by a source of current 20 in a circuitincluding a switch 2| runs at a constant speed. Through appropriategears 22 and 23 the motor I9 drives the shaft 24 and this, through anywell-known type of slip clutch, drives the arm I 1 carrying brushes I4and I8 when the arm I1 is not held stationary by the latch I6.

Brush I4 makes contact between one line of segments I5, 25 and 26 andanother line of segments I3 and 21. Likewise, brush I8 makes contactbetween one line of segments 28 and 29 and another line of segments 310and 3|. The line of segments 3D and 3| is adjustable with respect to theother lines of segments for purposes of orientation, which function isWell understood in the art and hence will not be further explainedherein.

Immediately after arm |1 has been unlatched it moves under control ofshaft 214 in a clockwise direction. Immediately, therefore, theconnection between segments I3 and I5 through brush I4 is broken andlatch magnet I2 is allowed to release. Immediately thereafter aconnection is established between segments I5 and 21 for the purpose ofapplying positive battery to the line 32, thus putting a spacingcondition on this line. The spacing condition is transmitted through therepeater 34 over line 35 through repeater 36, line 31 and receivingrelay 38 which is driven to its spacing contact. Relay 38 establishes aconnection from its spacing contact over stop segment 39, brush 48,segment 4I to latch magnet 42 and thence to negative battery, resultingin the energization of the latch magnet 42 and the movement of latch 43to free the arm 44.

The distributor shown in Fig. 3 operates like the distributor in Fig. 2though its segments are cut in a diierent manner. Here a motor 45 is runat a constant speed from a source of current 46 through a circuitincluding switch 41. The motor 45 drives a set of gears 48 and 49 tocause shaft 50 to rotate at a constant speed. The distributor arm 44 isassociated With the shaft 50 through a slip clutch and will rotate in aclockwise direction when freed by latch 43. This arm carries two sets ofbrushes. Brush 40 makes connections between the line of segments 39 and5| to 58, inclusive, and the line of segments 4I and 59 to 63, inclusiveand the brush 1I] makes connections between the line of segments 64 to61, inclusive,

and the line of segments 68 and 69. The arm 44 is constructed andarranged to complete one full revolution in slightly less time than thearm I1, so that if arm I1 is caused to rotate continuously without beingstopped by the latch I6 then arm 40 will become latched just in time tostart a new revolution as arm I1 reaches the point where it willnormally be unlatched.

In the latched position of arm 4 and for a short time after this arm isunlatched and starts to travel, brush 18 makes connection betweensegments 64 and 68 whereby relay 1| is energized. This relay serves inits energized position to lock relays 12 and 13 in their markingpositions and to open a locking connection for relays 14 and 15. Shortlythereafter brush 10 leaves seg- Y 'ment 64 and relay 1| thereforereturns to normal.

arm 86.

As the arm 44 continues to revolve, brush 4l) establishes a connectionbetween segments 53 and 6| for the purpose of selecting either station16 or station 11 to receive the code impulses about to be transmitted.If relay 38 is on its spacing contact at this time, then relays 14 and15 will move to their spacing contacts and a circuit from the armatureof relay 13 will be -established to the sending relay 18 and relays 14and 15 will lock on their spacing contacts through the back contact andupper armature of relay 1I. If relay 38 is on its marking contact atthis time, then relays 14 and 15 will remain on their marking contactsand a connection will be established from the armature of relay 13 tothe sending relay 19.

It should be particularly noted that the identiilcation signal resultsin the operation or nonoperation of relay 15 and that this is due to thedifferent character of such identiiication signal. It should be furthernoted that other means are contemplated within the scope of thisinvention, such as other relay arrangements responding to other types ofdifferent character signals which might include diierentialarrangements, marginal arrangements or even various alternating currenttuned arrangements. While the simplest type of polar arrangement isshown as an example, it is to be understood that the invention is not tobe limited thereto.

Returning now to the sending distributor, it

will be noted that as the arm I1 is unlatched and begins to move aconnection is established between segments I5 and 21 to put a spacingcondition on line 32 as before mentioned. As the arm I1 progresses, andin accordance with the setting of the before-described orientationmeans, a connection will presently be established by brush I 8 betweensegments 28 and 38 whereby battery is connected to the frontcontacts ofthe lower armatures of relays 5 and 9. Since it was assumed. thatstation A was in a condition to transmit, this connection will result inthe energizationl of latch magnet 89.

Station A is equipped with a tape transmitter consisting essentially ofa constant speed motor 83 driving a shaft 84 ythrough a slip clutch 85.When the latch magnet becomes energized,

vthe latch 8| is moved out of engagement with the cam 82 and shaft 84moves the distributor The distributor arm 86 is constructed and arrangedto make a complete revolution in approximately the same time as arm I1.lThe orientation device is so set that this tape transmitter is startedat such a time that the brush arm 86 is sweeping over the segmentsconnected to the tape contacts generally designated 81Y While the 'brushI8 is making connection between segments 2B and 21. While the brush arm86 is stationary and for a short time after it starts, 'a connection ismade from ground through the monitor printer 88 to the relay 3 3,holding this relay to its marking contact. Shortly thereafter arm 86passes over its start segment whereupon the connection to relay 33 isopened and relay 33 goes to spacing. It is at this time that brush I4 ismaking a connection between segments l and 21 and it is also at thistime that brush Q is making a connection between segments53 and I I'.

Since station A is sending, a spacing condition is put on line 32 bothby the relay 33 and by the relay 89 from its back contact, segment 25,brush I4, segment 21 to line 32. Therefore, relay 38 will be on itsspacing contact and station 15 will be selected.

If, on the other hand, station B had been sending, then at this timerelay 33 would have been marking and relay 89 would have been spacing,with the result that line 32 would have been marking, relay 38 wouldhave been marking and station 1'! would have been selected. Thus, thetime of the start pulse of station A or station B is used to transmitover the line a differentiation signal rather than a start-stop signal.

As the arm 44 passes over the pointwhere brush makes connection betweensegments 53 and 6 I', the brush 1D makes a connection between segments63 and 66 whereupon the selected relai7 18 or 13 is driven to spacing,thus sending a start signal to the selected station. As arms I1, 'M and86 advance, arm I1 reaches appoint where brush I4 bridges segments 25and 21. With station A transmitting, this connection is ineective sincesending relay 33 makes direct connection to line 32, but with station Btransmitting, this connection is effective as a means to place themarking and spacing signals from relay 39 on line 32. The distributorsare so timed that, as the arm'll at station A or the corresponding armat station B is passing over the middle part of its code segments, thebrush 40 will be passing over segments 54, 55, 5G, 51 and 58 and relay13 responding `to the action of relay 33 or relay 89 will transmitcorresponding mark or space signals to relay 18 or 19 and thus operatethe station receiving apparatus 16 or 11.

During the signaling period, brush I8 passes off segment 30, whereuponmagnet 8!) is released. At the receiving end the locally generated startpulse is ended by the movement of brush 1I! off segment 66 just beforethe first signaling pulse is received.

After the five signaling pulses have been transmitted, 'brush I4 bridgessegments I3 and I5. whereupon latch magnet again becomes energized toallow arm I1 to continue on for transmitting the next character.providing tape switch 3 is still closed and station B still remains in anon-transmitting condition.

At the receiving end, brush lili bridges segments 39 and 4I preparing acircuit for latch. magnet d2, but, as heretofore pointed out, arm Mreaches the latching position slightly ahead of arm I1 and hence willlatch. Shortly after brush 4Q bridges segments 39 and 4I, brush 10 makesa connection between segments 64 and B8, with the result that relay 1Iis energized. Relays 12 and 13 are thereupon locked in a markingposition and relays 14 and 15, if in a spacing position, are released totheir marking positions.

Let us now assume that both station A and station B close their tapeswitches at exactly the Yso same time. Relays 4 and 8 will becomeenergized simultaneously. Relay 8, however, will cause the operation ofrelays 9 and II) and these relays will lock to the front contact andupper armature of relay 8. Relay I I will become energized in a circuitfrom positive battery, segment I5, brush I4, segment i3, relay I I,front contact and armature of relay IIJ, front contact and upperarmature of relay liIto ground. Relay II releases relay 8 andthisvrelay'then closes a circuit for relays 5 and 6, which -lock to theupper armature of relay 4. Relays 9, I0 and II release, and lnow thecircuit for relay 8 is again closed but this relay is slow to operate.In the meantime, Ythe latch magnet I2 has released arm I1 vso thatbefore relay 8 could again operate to close va circuit for relay 1,brush I4 yhas passed beyond segment I3. Relay 1 will not operate inseries with latch magnet I2. Therefore, if both stations A and B startto transmit simultaneously, station A will take command.

After the arm I1 has almost completed a revolution,brush I4 againbridges -segments I3 and I5. Now relay 1 operates and causes the releaseof relays i5, 6 and finally itself. When relay 6 releases, relays 9 andI0 are operated and a circuit is prepared for relay II. However,relay'lI, like rel-ay 8, is slow to operate and will not complete thecircuit for relay I I until brush I4 has passed beyond segment I3.Therefore, station Bvnow has command of the circuit and will transmit acharacter.

v When the brush I4 vagain bridges segments I3 and I5, relay II willoperate and transfer command of the circuit lto station A. In thismanner station A and station B alternately have command of the circuitand each in turn sends a character. Y

It will be understood that if either station has exclusive command ofthe circuit then that station will continuously transmit, using the fulltimer-ofthe transmission line. If the other station then cuts in, thesequence of alternating transmission will take eiectv as described, assoon 'as brush Id reaches segment I3 and cause a change-over from onetransmitting station tothe other! p While this description sets forththe circuit arrangement for only two transmitting stations and tworeceiving stations, it will be understood that .the invention is notlimited to such a specic arrangement but comprehend-s alternativearrangements where a sequence circuit is used to alternately put in aItransmitting condition those stations which are ready to transmit andwhich uses the usual time of the start pulse to transmit a stationidentifying signal.

What is claimed is:

:1. A telegraph system comprising a main line.

start-stop apparatus connected to each end of said main line, extensionlines connected to said start-stop apparatus each having means totransmit stop-start and permutation code impulsesY ran-d supervisoryequipment operatively connected to said start-stop apparatus forsubstituting a different character signal for identifying the a-ctiveextension line with each series of impulses received over saidexten-sion lines in place of the start and stop impulses from saidextension lines.

2. In a communication system, a plurality of subscribers stations at onelocality linked to a like plurality of Subscribers station-s at anotherlocality over seemingly direct individual and permanently establishedconnections, a common channel for said -connections between saidlocalities, and means to .identify e-ach connection rendered effectiveover said common ch-annel comprising apparatus for controlling thecharacter of a single impulse accompanying each code group of impulses.

3. In a communication system, a plurality of subscribers stations at onelocality linked to a like plurality of subscribers stationsat anotherlocality over seemingly direct individual and permanently establishedconnections, a common channel for said connections between saidlocalities, means for rendering each of said connections effective inturn, and signal transmitting means selectively controlled by saidstations for identifying said connections asthey are rendered effectivecomprising an instrumentality for controlling the character of a singleimpulse accompanying and having a fixed time relationship with theimpulses of each code group of impulses.

4. In a communication system, a plurality of subscribers stations at onelocality linked .to a like plurality of subscribers"stations at anotherlocality over seemingly direct individual and permanently establishedconnections, a common channel for said -connections between 'saidlocalities, means at each of said stations for transmitting intelligenceby start-stop permutation code signals, start-stop means for relayingsaid signals over said common channel, means for marking each of saidconnections a-s-in a condition ready to transmit, a sequence circuit forappropriating said common channel exclusively to each of saidconnections in turn and means for substituting in said common channel adifferent character connection identilcation signal for the start signalpreceding each permutation signal group upon appropriation of saidcommon channel.

5. In a -communication system, a plurality of subscribers stations atone locality linked to a like plurality of subscribers stations atanother locality'over seemingly direct individual and permanentlyestablished connections, a common channel for said connections betweensaid localities, a group of relays individual to each said stationforming a sequence circuit for successively appropriating said commonchannel exclusively to said connections, means controlled by said relaysfor` diierently identifying each sai-d connection and means responsivethereto for transmitting identication signals over said common channelat the start of each period of appropriation, said identiiicationsignals comprising signals of fdiierent character invariably occupyingthe same time period in the total period of appropriation.

6. In a communication system, a plurality of subscribers stations at onelocality linked to a like plurality of subscribers stations at anotherlocality over seemingly direct individual and permanently establishedconnections, a common channel between said localities, a sequencecircuit for successively appropriating sai-d common channel -to activeones of said connections, means controlled by said sequence circuit foreach said connections, means responsive to the appropriation of saidcommon channel for iirst sending an appropriation signal, second,sending an identification signal different in character for each saidconnection and controlled by said rst means and, third, sendingcommunicationv signals, said various signals invariably occupying thesame relative time periods in said cycle of signaling operations. V 1

7. In a communication system, a plurality of subscribers stations at onelocality linked to a like plurality of subscribers stations at anotherlocalityover seemingly direct individual and permanently establishedconnections, a common channel for said connections between saidlocalities, start-stop apparatus for communicating over said commonchannel, a group of relays at the transmitting end individual to eachstation thereat and forming together a sequence circuit for seriallyappropriating said common channel exclusively to the active ones of saidconnections, said sequence circuit functioning further to maint-ain saidcommon channel constantly in use so long as at least one of saidconnections is active, means under control of said start-stop apparatusfor transmitting an appropriation signal followed by an identificationsignal before each period of communication, said identification signalbeing transmitted invariably at the same point in the cycle of operationof said start-stop apparatus.

FRANK H. HANLEY.

